Hasil untuk "Chemical technology"

A. Bridgwater

G. Hoogers

Kenneth Helrick

S. Tsang, Yuhui Chen, P. Harris et al.

G. Whitesides

E. Beckman

M. Maricq

M. Schäferling

Shaohan Chen, Tim Langhorst, Julian Nöhl et al.

Chemicals are embedded in nearly every aspect of modern society, yet their production poses substantial sustainability concerns. Achieving a sustainable chemical industry requires detailed Life Cycle Assessment (LCA); however, current assessments face many unknowns due to limited, partly inconsistent, and untransparent data coverage since existing Life Cycle Inventory (LCI) databases account for only a tiny fraction of traded chemicals. Here, we introduce the Chemical RetrosYnthesiS for Transparent Assessment of Life-cycles (CRYSTAL) framework, which automatically generates consistent and transparent LCI data for organic chemicals based on their molecular structure using retrosynthesis and machine-learned gate-to-gate inventories. Using the predictive power of CRYSTAL, we create a consistent database for more than 70000 organic chemicals, comprising over 110000 transparent LCI datasets that quantify both feedstock and energy demands, together with associated auxiliary materials, biosphere flows, and waste flows. From this comprehensive database, we identify 50 key environmental hotspots driving high impacts of organic chemical production across multiple environmental categories and pivotal hub chemicals that are most critical for downstream chemical production. In providing this comprehensive data foundation, the CRYSTAL framework offers systematic guidance for targeted engineering and policy interventions. Its transparent, modular nature is designed to shift chemical LCA from a reliance on "unknown unknowns" to a collaboratively improvable mapping of "known unknowns".

Sudheesh Parathakkatt, Vaisakh Kizhuveetil, Gokul G. K. et al.

Worm-like micelles (WLMs) are dynamic, self-assembling supramolecular structures that exhibit complex viscoelastic behaviour due to their ability to undergo reversible scission, fusion, branching, and sequence rearrangement. This review provides a comprehensive analysis of recent theoretical advances in modelling WLM rheology, from classical reptation–scission theories to modern stochastic simulations and multi-scale population-balance frameworks. A central challenge addressed is the rheological indistinguishability of competing models under linear conditions, which renders inverse modelling ill-posed and necessitates the integration of experimental data, such as cryogenic transmission electron microscopy (cryo-TEM), small-angle neutron scattering (SANS), and flow birefringence, to constrain theoretical predictions. The article further explores the limitations of conventional models in capturing nonlinear responses, including shear banding and extensional strain hardening, and emphasizes the need for spatially resolved, structurally informed constitutive equations. Emerging tools, including neural networks and hybrid modular frameworks, are identified as promising solutions for bridging microscopic rearrangement dynamics with macroscopic flow behaviour. Ultimately, the development of predictive, physically grounded WLM models will be essential for advancing applications in formulation science, smart materials, and industrial processing.

Ana Paula Yumi Nishimura, Fernando Augusto Pedersen Voll, Nadia Krieger et al.

Kinetic models are important tools for guiding the design and optimization of lipase-catalyzed processes. These processes follow the Ping Pong bi bi mechanism, for which mechanistic kinetic equations can be derived. However, when there are several competing reactions, fully mechanistic models contain a large number of parameters, making it difficult to obtain reliable estimates, so simplified models are necessary. We present a two-step approach to developing semi-mechanistic models of such processes. The first step involves the estimation of the selectivities of the enzyme, using profiles for the reaction species plotted against the degree of reaction, while the second step involves empirical fitting to the same data, but plotted as a function of time. We demonstrate this two-step approach through four case studies based on the literature data for the lipase-catalyzed esterification of fatty acids with trimethylolpropane to produce biolubricants. The semi-mechanistic models were able to describe the data well. Our approach has the advantage of allowing selectivities to be estimated without confounding effects from phenomena such as enzyme denaturation and inhibition. It therefore provides a promising framework for developing models of enzyme-catalyzed processes that obey Ping Pong bi bi kinetics.

A. Lyngfelt

Shaowen Xu, Jeffrey R. Reimers, Fanhao Jia et al.

Layers of perovskites, found in 3D materials, 2D heterostructures, and nanotubes, often distort from high symmetry to facilitate dipole polarisation that is exploitable in many applications. Using density-functional theory calculations, ferroelectricity in bilayers of the 2D materials PbTiO3 and SrTiO3 is shown to be controlled by bond breakage and formation processes that act as binary switches. These stacking-dependent processes turn on and off as a function of relaxation from high-symmetry structures and the application of biaxial strain, and their concerted rearrangements lead to low energy barriers for ferroelectric polarisation switching. Structures with symmetry intermediate between high-symmetry octahedral forms and low-symmetry ferroelectric forms are identified, allowing the intrinsic processes associated with traditional "ferrodistortive" and "antiferrodistortive" distortions of TiO6 octahedra to be identified. Ferrodistortive-mode activity is shown to be generated by the simultaneous application of two different types of curvilinear antiferrodistortive motions. In this way, four angular variabes control polarisation switching through the concerted making and breaking of chemical bonds. These subltities make the polarisation sensitive to chemical-environment and temperature effects that manipulate strain and structure, features exploitable in futuristic devices.

Nur Tarımeri Köseer, Mustafa Kemal Sezgintürk

Abstract Hereditary angioedema (HAE), an autosomal dominant disease that may be fatal in the larynx and gastrointestinal tract, can affect the skin and mucosal surfaces. Indium tin oxide-polyethyleneterephthalate (ITO-PET) electrode based on biosensor is put up in this study to detect C1-Inhibitor (C1-INH). The ITO-PET electrodes were surface have undergone a cleaning procedure. Hydroxylation (NH4OH, H2O2, H2O) was applied to the electrode surfaces. The ITO-PET electrode surfaces were then treated with 3-Aminopropyltrimethoxysilane (3-APTES). Crosslinking with glutaraldehyde was the following step. The concentration of 3-APTES, the concentration of anti-C1-INH, and the length of time that C1-INH was incubated were the ideal conditions. It conducted immobilization, optimization, and analysis stlod udies using techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The linear range, repeatability, reproducibility, regeneration studies, single frequency studies (SFI), and storage of life of the biosensor were carried out in characterization studies. It was discovered that the linear range of the immunosensor was 2 fg/mL to 1500 fg/mL. It discovered the biosensor's (11 weeks) storage life. The LOD value calculated as a result of the study is 0.23 fg/mL and the LOQ value is 0.26 fg/mL. The biosensor was tested using the (SWV) square wave voltammetry technique (0–1.5 V, equal time: 2, frequency: 25 Hz, pulse size: 25 mV). The interaction between antibody C1-INH and C1-INH antigens was observed using a single frequency technique (SFI).The final stage was testing the biosensor on commercial serum studies.

Lanlan Sun, Y. Diaz-Fernandez, T. Gschneidtner et al.

The use of single molecules in electronics represents the next limit of miniaturisation of electronic devices, which would enable us to continue the trend of aggressive downscaling of silicon-based electronic devices. More significantly, the fabrication, understanding and control of fully functional circuits at the single-molecule level could also open up the possibility of using molecules as devices with novel, not-foreseen functionalities beyond complementary metal-oxide semiconductor technology (CMOS). This review aims at highlighting the chemical design and synthesis of single molecule devices as well as their electrical and structural characterization, including a historical overview and the developments during the last 5 years. We discuss experimental techniques for fabrication of single-molecule junctions, the potential application of single-molecule junctions as molecular switches, and general physical phenomena in single-molecule electronic devices.

Mohammed Loukili, Ludovic Jullien, Guillaume Baffou et al.

Temperature gradients represent energy sources that can be harvested to generate steady reaction or transport fluxes. Technological developments could lead to the transfer of free energy from heat sources and sinks to chemical systems for the purpose of extraction, thermal batteries, or nonequilibrium synthesis. We present a theoretical study of 1D chemical systems subjected to temperature gradients, for sustaining nonequilibrium chemical fluxes. A complete theoretical framework describes the behavior of the system induced by various temperature profiles. An exact mathematical derivation was established for a simple two-compartment model and was generalized to arbitrary reaction-diffusion systems based on numerical models. An experimental system was eventually scaled and tuned to optimize either nonequilibrium chemical transport or reaction. The relevant parameters for this description were identified; they focused on the system symmetry for chemical reaction and transport. Nonequilibrium thermodynamic approaches lead to a description analogous to electric circuits. Temperature gradients lead to the onset of a steady chemical force, which maintains steady reaction-diffusion fluxes moderated by chemical resistance. The system activity was then assessed using the entropy production rate as a measure of its dissipated power. The chemical characteristics of the system can be tuned for general optimization of the nonequilibrium state or for the specific optimization of either transport or reaction processes. The shape of the temperature gradient can be tailored to precisely control the spatial localization of active processes, targeting either precise spatial localization or propagation over large areas. The resulting temperature-driven chemical system can in turn be used to drive secondary processes into either nonequilibrium reaction fluxes or concentration gradients.

Pongsiri Julapong, Palot Srichonphaisarn, Thidarat Meekoch et al.

The use of washing machines to wash textiles gradually breaks down synthetic fibers like polyethylene terephthalate (PET) or polyester (PES) in diverse clothing materials, a process that is growing in notoriety because it generates microplastics (MPs). In this study, we investigated the emission of microfibers, including both microplastic fibers (MPFs) and natural fibers (MFs), from top-loading washing machines. Our investigation focused on four popular textiles with prevalent weave structures (plain, satin, and twill): (i) PES, (ii) tetron cotton (TC), (iii) chief value cotton (CVC), and (iv) cotton (CO) fabrics. This study also examined the effects of textile weight and detergent dosage on MF emissions. After washing, MFs were collected through filtration, and their concentrations were determined using micro-Fourier Transform Interferometry (μFTIR). The results showed varying concentrations of MFs in the washing effluent depending on the type of textile. Specifically, CVC exhibited the highest emission at 4022 particles/L, followed by TC, PES, and CO at 2844 particles/L, 2382 particles/L, and 2279 particles/L, respectively. The hydrophobic nature of PES makes this type of textile prone to rapid degradation in detergent-rich environments, leading to high MF emissions. Additionally, the mechanical properties of textiles, such as tensile and bending strengths, may play a crucial role in the generation of MFs in washing machines. Textiles made of CO with twill weaves demonstrated superior strength and correlated with lower emissions of MFs. In comparison, textiles made of CVC and satin weave exhibited lower mechanical properties, which could explain their high emissions of MFs. Finally, the MF emissions of textiles composed of PES and TC, which are plain weaved, could be attributed to their intermediate mechanical properties compared with those of CVC and CO.

Yuchen Luan, Fukun Sun, Jiaen Zhou

Satellite fog computing (SFC) achieves computation, caching, and other functionalities through collaboration among fog nodes. Satellites can provide real-time and reliable satellite-to-ground fusion services by pre-caching content that users may request in advance. However, due to the high-speed mobility of satellites, the complexity of user-access conditions poses a new challenge in selecting optimal caching locations and improving caching efficiency. Motivated by this, in this paper, we propose a real-time caching scheme based on a Double Deep Q-Network (Double DQN). The overarching objective is to enhance the cache hit rate. The simulation results demonstrate that the algorithm proposed in this paper improves the data hit rate by approximately 13% compared to methods without reinforcement learning assistance.

N. E. Posokina, O. V. Bessarab, O. V. Karastoyanova et al.

Agaricus bisporus are the most common cultivated mushrooms. Champignons are a source of chitin, glycogen and minerals, and also have attractive organoleptic properties. Physicochemical and organoleptic characteristics of fresh Agaricus bisporus undergo significant changes during storage due to moisture transpiration, respiration and oxidative processes. The purpose of this work was to study the influence of storage conditions of cultivated champignons with unstained cap epithelium on the dynamics of their physicochemical parameters, as well as its relationship with changes in organoleptic parameters. The mushrooms were stored in refrigerated chambers at a constant temperature of +2 °C and +6 °C in polypropylene trays placed in bags made of biaxially oriented polypropylene (BOPP) perforated film and polyethylene (PE) film without perforation. Under all storage conditions studied, the nature of the dynamics of physicochemical parameters was close to linear (with the exception of the humidity of fruiting bodies when stored in PE film) — the calculated values of the Pearson correlation coefficient ranged from 0.67 to 0.97. Using two-factor analysis of variance, the influence of both packaging material and storage temperature on the dynamics of soluble solids content and mushroom tissue density was confirmed. When stored in PE film without perforation, a more intense negative dynamics of these criteria was observed compared to storage in perforated BOPP film. The identified difference is explained by the fact that in packaging made of PE film without perforation, conditions for anaerobic respiration were formed by the end of storage — the oxygen content decreased from 20.5% to 1.5–2.5%, which also contributed to the activation of decay processes. With increasing storage temperature, a more intense change in physicochemical parameters was observed, which was associated with an increase in metabolic rate. The relationship between the dynamics of all studied physicochemical quality markers and the dynamics of sensory assessments (with the exception of the marker "content of soluble solids" when stored in a perforated BOPP film at a temperature of 2 °C) has been statistically confirmed. Based on the results of the studies, the applicability of the criteria “humidity of fruiting bodies”, “content of soluble dry substances” and “density of fungal tissue” as markers for assessing the quality of cultivated Agaricus bisporus was confirmed.

Sneha Tomar, Vinod Kumar Singh

In this study, two different metal-organic frameworks (MOFs) were synthesized using copper and cobalt metal ions with benzenedicarboxylic acid (bdc) as a common ligand. The prepared MOFs were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy-energy dispersive spectroscopy. Also, the electrochemical characteristics were analyzed using cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy methods. Structural characterizations indicate that Co-bdc MOF is composed of three-dimensional non-uniform colloids and Cu-bdc MOF has a regular three-dimensional cuboidal structure, possessing good crystalline structure. The Cu-bdc MOF exhibited a maximum specific capacitance of 171 F/g, while Co-bdc MOF showed 368 F/g at the current density of 1 A/g. The solution resistance for the Co-bdc MOF was 0.09 Ω in comparison to 1.25 Ω for the Cu-bdc MOF. Also, the Co-bdc MOF demonstrated better cycling performance by retaining 85 % of its capacity after 2000 charge-discharge cycles. In contrast, the stability of the Cu-bdc MOF was lower, with only 78 % retention in capacity. Conclusively, the Co-bdc MOF demonstrated superior specific capacitance, lower resistance, and enhanced cyclic stability in 3 M KOH electrolyte system.